The hacker dojo runs all of its servers and applications on BSD (not sure which one), and they have a european BSD magazine in the Loo, so I took notice when news came out today about VirtualBSD's 9.0 release. This is FreeBSD with drivers etc. optimized to run in VMWare - and distributed as an image (instead of an installation CD) - which is sort of the new LiveCD. Just download the OS as a program and run it (not sure if VMWare needs to be installed, but VMWare Player is free, which I have used and works fine, so no worries there).
VirtualBSD is one of the first OS's I've seen that has been optimized to run inside a VM. I'm not sure if it in fact works outside of a VM - it may lack the drivers to do so as an optimization, though a USB stick should be able to transfer files if for some reason you wanted to run native. (USB sticks are supported quite well in VMWare, wiht default mode such that if the VM window has focus, then any USB stick that is plugged into the host is routed through to the guest and in fact not available to the host... I love it!)
BSD is interesting - as with any BSD license you can modify the source code and distribute the resulting program without any requirement to distribute the source. In some ways the BSD license is considered the most open of the open source licenses (MIT's a close second, which requires the maintenance of the license text in any distributions).
One of the biggest problems with software is versioning - just try to compile a large program that hasn't been updated in a few years in a new Linux installation and you probably will come to the same sad realization I have: A few of the updated compiler toolchain's components probably have an incompatible version for the given software. This is one reason I have been carefully considering a switch to Mac - the pseudo-BSD OS that lies underneath the GUI environment has only major release versions, and is only updated once or a few times per year. The build environments in future releases of Mac OS are quite likely to be able to compile old programs, given those programs were compatible with the BSD-like Mac OS system at some point. As a practical engineer, I have to trade the nobility and anarchy of the GPL'd Linux for the Fuhrer's "it just works" system almost every time. </backhanded Apple complement> :-D